Evaluation of Evaporative Cooling Chamber Using Computational Fluid Dynamics

Abstract

Global temperatures are affecting almost all aspects of our society, including food security. A rise in temperature leads to a decrease in relative humidity. In Kenya, about 25–45% of fruits and vegetables perished because of inappropriate storage facilities. This is especially worrying among rural farmers. The primary objectives of this study were to evaluate the performance of the pumice evaporative cooling chamber with energy savings and thermal control and to simulate the storage chamber using a Computational Fluid Dynamics (CFD) model to predict storage temperature. A pumice evaporative cooling chamber of 14.58 m3 capacity, powered by solar energy, was designed and constructed at Jomo Kenyatta University of Agriculture and Technology for the study. Temperature, relative humidity, solar radiation, and wind speed were measured for natural convection, forced convection, evaporative, evapotranspiration, and combined cooling systems. The evaporative cooling data was used to develop a CFD model to predict the storage temperature. The three-dimensional CFD geometry was developed and used to simulate the cooling chamber with the Shear-Stress Transport (SST) k-omega model. The result was compared to experimental data and showed that, with no artificial influence on the cooler, the difference between ambient and storage temperature was 11.47 ᴼC, and the ambient and storage relative humidity was 42.44%. The cooling pad was 83% efficient. The ambient and storage temperature difference was 13.64ᴼC, and humidity increased by 64.44% and 98.6%, respectively, for evaporative cooling. The CFD model predicted result was compared against experimental data with a 98% confidence for evaporative cooling and there was no significant difference. The study provided valuable guidelines for the design of an evaporative cooling system with efficient energy savings for the storage of fruits and vegetables. Keywords: Computational fluid dynamics,modelling, Evaporative cooling, Postharvest loss